Proton The Proton launch vehicle has been the medium-lift workhorse of the Soviet and Russian space programs for over forty years. Although constantly criticized within Russia for its use of toxic and ecologically-damaging storable liquid propellants, it has out-lasted all challengers, and no replacement is in sight. More...

Proton 11S861 Lox/Kerosene propellant rocket stage. Loaded/empty mass 17,300/2,300 kg. Thrust 85.02 kN. Vacuum specific impulse 352 seconds. Also known as Block DM-2 (different from commercial Block DM2 (no hyphen!)), article number 11S861. Commercial version designated Block DM1 and is equipped with Saab payload adapter for insertion of AS 4000 bus spacecraft into geosynchronous orbit. With improved guidance system as compared to 11S86, originally designed for insertion of military spacecraft into geosynchonous orbit. Used from 1982 to present. More...